The present invention relates to an improved photoelectric converting device and more particularly to a thin and elongated photoelectric converting device to be in use for facsimile equipment, remote copier or other similar image processing apparatus.
Photodiode, phototransistor, CCD sensors and others have been heretofore known as typical photoelectric converting devices in which an optical signal is converted into an electric signal. These conventional photoelectric converting devices usually have small photoelectric surfaces smaller than an image to be read out and therefore it is necessary to provide an optical system for reducing the image.
In view of the foregoing inconvenience with the conventional image processing apparatus there has been proposed a thin, elongated photoelectric converting device adapted to read out an original image as it is without any optical reduction.
An example of such conventional photoelectric converting device is as illustrated in FIGS. 1(A) and 1(B). In the drawings, FIG. 1(A) is a perspective view illustrating the whole structure of the film type photoelectric converting device and FIG. 1(B) is a perspective view of the device shown in a disassembled state. As will be apparent from the drawings, the film type photoelectric converting device as identified with reference numeral 90 comprises a plurality of divided electrodes 92 (four divided electrodes in the illustrated example) formed on an electric insulative base board 91, a layer of photoelectric film 93 coated over a portion of said divided electrodes 92 and a layer of common electrode 94 deposited on said photoelectric film 93.
The insulative base board 91 is made of glass, ceramic, metallic plate with the surface being coated with insulating material, silicon wafer or the like material. Aluminum, cromium, plutinum, composite film of tin oxide (Sn O.sub.2) and indium oxide (In.sub.2 O.sub.3) (hereinafter referred to as ITO film) or the like material is employed for the divided electrodes 92. Hydrided amorphous silicon (inclusive of n type only with hydrogen included and P type with an acceptor doped therein), selenium-tellurium-arsenic (Se--Te--As), cadmium sulfide (Cd S), cadmium selenide (CdSe), cadmium telluride (CdTe) or the like material is employed for the photoelectric film 93. Further, ITO film, tin oxide (Sn O.sub.2), indium oxide (In.sub.2 O.sub.3) aluminum (Al), chromium (Cr), gold (Au) or the like material is employed for the common electrode 94.
The charcteristics of the conjunction sections between the divided electrodes 92 and the photoelectric film 93 as well as between the latter and the common electrode 94 is determined by a combination among the above-mentioned materials. Whether these characteristics are to be made ohmic, in an inhibitive type or in a diode type will be decided depending on the signal read-out circuit.
Further, the conventional film type photoelectric converting device is illustrated in FIGS. 2 and 3, wherein FIG. 2 is a plan view of the device as seen in the direction identified with an arrow mark II in FIG. 1(A) and FIG. 3 is a front view of the same as seen in the direction identified with an arrow mark III in FIG. 1(A). In FIGS. 2 and 3, the whole surface of the photoelectric film 93 does not perform photoelectric conversion, but only a light beam receiving section 95 which is defined by an area where the upper common electrode 94 is superimposed on the lower divided electrodes 92 in a cross relation performs the photoelectric conversion.
It should be noted that there is necessity for making at least one of the electrodes 92 and 94 of transparent material so as to assure that light beam coming from the outside can be introduced thereinto and moreover in the case where a light beam is emitted from the side of the divided electrodes 92, the insulative base board 91 should also be made of transparent material.
Referring now to FIG. 4 which illustrates an example of a signal read-out circuit, each of the divided electrodes 92 is connected to the one input terminal of an amplifier 83 via a plurality of semiconductor switches 82, and the common electrode 94 is connected to the other input terminal of the same via a power source 81. Thus, one of the light beam receiving sections 95 is selected out by the corresponding semiconductor switch 82 and a signal generated from the selected section is outputted from the amplifier 83 after it is amplified therein.
Referring to FIG. 5, the conventional film type photoelectric converting device as constructed in the above-described manner is arranged, for instance, in a facsimile telegraphic apparatus. An original (not shown) is delivered downward from the above by means of a roller 88 adapted to rotate in the direction identified with an arrow mark F1 in FIG. 5 while light beam is emitted in the direction of an arrow mark F2 toward the downwardly moving original on the roller 88 from a light source 89. The light beam is then reflected in the direction of an arrow mark F2' ,from the original and enters the photoelectric converting device 87. Auxiliary scanning to be effected in the direction of feeding of the original is mechanically undertaken by a motor (not shown), whereas main scanning to be effected at right angle relative to said auxiliary scanning is electrically undertaken by the semiconductors in FIG. 4.
As will be readily understood from FIGS. 1 to 3, any irregularity at the end part of the common electrode 94 causes unfavorable effect on the reproduction of image because a size of the light beam receiving section 95 is closely related to image reproductivity.